Synthesis of BaZrS ₃ Perovskite Thin Films via Different Solid BaS x Intermediate Phases

High Resolution Image Download MS PowerPoint Slide The BaZrS 3 perovskite has emerged as a promising compound for photovoltaic (PV) applications due to its unique optoelectronic properties, stability, and abundance of the constituent elements. Recent research has devoted considerable effort to decreasing the processing temperature to facilitate the integration of BaZrS 3 thin films into optoelectronic devices. In this context, the formation of a barium polysulfide liquid flux as an intermediate phase is anticipated to promote BaZrS 3 synthesis. This study investigates whether solid binaries can also accelerate the process at lower temperatures, i.e., below melting. To address this question, Ba–Zr precursors were sulfurized under various conditions that favor the formation of distinct solid BaS x intermediate phases during BaZrS 3 synthesis, achieved by deliberately selecting processing temperatures below the melting points of any of the involved binary sulfides. The crystallinity of the resulting BaZrS 3 thin films is evaluated by X-ray diffraction and transmission electron microscopy, revealing that the sulfurization conditions that favor solid BaS 3 offer a greater advantage for BaZrS 3 formation than those that promote BaS 2, which in turn prove more favorable than those that favor BaS. Moreover, by varying sulfur partial pressure and sample temperature during sulfurization, this study disentangles the effects of these two parameters on BaZrS 3 crystallization: the results indicate that the sulfurization conditions that favor BaS 3 effectively promote BaZrS 3 nucleation, while high temperatures predominantly enhance grain growth.